JP4239397B2 - Start control device for internal combustion engine - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an apparatus for controlling start-up of an internal combustion engine, and is particularly suitable for use in an in-cylinder injection internal combustion engine that injects fuel directly into a combustion chamber to raise the temperature of an exhaust purification catalyst by fuel injection control during start-up. The present invention relates to an internal combustion engine start control device.
[0002]
[Prior art]
Recent internal combustion engines (hereinafter also referred to as engines) are equipped with an exhaust purification catalyst in the exhaust system of the engine in order to purify exhaust gas. Generally, this catalyst is activated and functions only when the temperature is raised to a predetermined high temperature region. Therefore, since the catalyst is at a low temperature when the engine is started, the catalyst is heated until the temperature of the catalyst rises to a predetermined temperature range due to the heat of the exhaust gas itself or the heat generated by burning unburned components in the exhaust gas near the catalyst. Does not function and exhaust gas purification is not performed.
[0003]
Therefore, various technologies have been developed to promote the temperature rise of the catalyst when starting the engine and to purify the exhaust gas more quickly after the start.
For one thing, paying attention to the fact that the exhaust gas does not dissipate as far as the upstream side of the exhaust passage, and that the temperature of the exhaust gas is high, combustion separate from the normal catalyst (underfloor catalyst) A small auxiliary catalyst is provided near the chamber (that is, where the exhaust temperature is high). Immediately after start-up, the auxiliary catalyst is efficiently heated with a relatively high temperature exhaust gas to quickly raise the temperature. There is one in which exhaust gas can be purified by an auxiliary catalyst activated by.
[0004]
Also, if unburned components remain in the exhaust gas, pay attention to the fact that the unburned components burn in the exhaust passage or on the catalyst and the temperature of the catalyst is increased by this heat, A technique for controlling fuel injection so that unburned components remain in the exhaust gas immediately after startup has also been developed.
In particular, in the case of a direct injection internal combustion engine, since the timing of fuel injection can be set freely, a technique has been developed to control the fuel injection and to quickly raise the catalyst temperature.
[0005]
For example, in Japanese Patent Laid-Open No. 10-121515, as a technique related to a direct injection internal combustion engine, additional fuel injection different from fuel injection for main combustion is performed from the initial stage to the middle stage of the expansion stroke. There has been proposed an additional fuel that is burned after the main combustion to raise the exhaust gas temperature and promote warm-up of the catalyst for early activation. In this case, since the second combustion (sub-combustion) is performed after the main combustion in one combustion cycle, such a combustion mode is referred to as two-stage combustion.
[0006]
Further, when additional fuel injection is performed in the expansion stroke as in this technique (Japanese Patent Laid-Open No. 10-121515), the additionally injected fuel does not contribute to the output of the internal combustion engine at all. Such additional fuel injection over a long period is not preferable in terms of fuel consumption. Therefore, for example, as disclosed in Japanese Patent Laid-Open No. 2000-240485, when the temperature of the catalyst device is required, the air-fuel ratio of the engine is slightly leaner in the vicinity of the stoichiometric air-fuel ratio than in the vicinity of the stoichiometric air-fuel ratio ( There has been proposed a technique for performing stratified combustion by injecting fuel directly into a combustion chamber during a compression stroke so that this is called “light lean”. The combustion mode in this case is referred to as compressed slender lean combustion.
[0007]
Thus, when fuel is injected during the compression stroke so that the air-fuel ratio of the engine is close to the stoichiometric air-fuel ratio and stratified combustion is formed, the fuel is concentrated in one place and the air-fuel ratio is locally rich. While incomplete combustion occurs due to the air-fuel ratio, a large amount of carbon monoxide (CO) is generated. On the other hand, excess oxygen (O ₂ ), So these CO and O ₂ Are discharged into the exhaust passage at the same time, and the CO and O discharged in this way ₂ Both reach the catalytic device via the exhaust passage and then, by the action of the catalyst, CO and O ₂ Cause an oxidation reaction, and the heat of the reaction raises the temperature of the catalyst device satisfactorily.
[0008]
Further, as in the above-described technique (Japanese Patent Laid-Open No. 10-121515), when additional fuel injection is performed in a direct injection internal combustion engine, the time until the catalyst central temperature rises and the catalyst is activated, Although it can be greatly shortened as compared with the conventional port injection type engine, there is a problem that the unburned HC is released into the atmosphere until the catalyst is activated.
[0009]
Therefore, as disclosed in Japanese Patent Application Laid-Open No. 11-294157, a volume part (or a retention chamber) is provided in the exhaust manifold so that the exhaust gas stays in the volume part, and the exhaust gas is discharged during the retention. A technique is disclosed in which unburned additional fuel (unburned HC) that flows in along with gas is reburned.
According to this technology, it becomes easy to re-combust additional fuel (unburned HC) that flows out to the outside together with the exhaust gas, and the discharge of unburned HC into the atmosphere until the catalyst becomes activated is reduced. In addition, the temperature of the exhaust gas heated by the injection of additional fuel during the expansion stroke can be further increased by reburning the unburned HC in the volume portion, and the temperature of the catalyst can be increased. You can also speed up.
[0010]
When these technologies are integrated, a catalyst is provided close to the combustion chamber on the upstream side of the exhaust passage (ie, a close catalyst is provided), and a volume portion (retention chamber) is provided in the exhaust passage upstream of the close catalyst. Thus, a configuration in which the above-described control of the two-stage combustion or the control of the compression slight lean combustion is applied to this.
[0011]
[Problems to be solved by the invention]
By the way, a configuration in which the above-described technologies are integrated, that is, a technology that provides a proximity catalyst and a volume portion (retention chamber) to control two-stage combustion and / or compression sludge lean combustion in an actual engine. When it is applied, it turns out that a sufficient effect can be obtained in the case of an engine with a small displacement, but a sufficient effect cannot be obtained or the catalyst is damaged in an engine with a large displacement. did.
[0012]
FIG. 9 shows the exhaust manifold when the engine having such a configuration is started. Hol Is a graph showing the change over time in the temperature inside the exhaust (exhaust manifold), the catalyst temperature, and the exhaust gas purification efficiency. Each solid line relates to a small displacement engine, and each chain line (one point) chain Line) relates to a large displacement engine. The horizontal axis represents time, and the two-stage combustion and the compressed slite lean combustion are shown in correspondence with each other above.
[0013]
As shown in the figure, in the small displacement engine, the exhaust gas purification efficiency is improved immediately after starting, but in the large displacement engine, the improvement in the exhaust gas purification efficiency is slow, and in the case of the large displacement engine, It can be seen that immediately after the engine is started, the exhaust gas purification efficiency is lower than that of the small displacement engine.
Looking at the temperature in the exhaust manifold, the temperature increase of the large displacement engine is slower than that of the small displacement engine, and the temperature level is low overall. Looking at the catalyst temperature, the temperature increase of the large displacement engine is slower than that of the small displacement engine, but in the small displacement engine, the catalyst reaches the activation temperature (the lower temperature limit value at which the catalyst becomes active). However, in a large displacement engine, after the catalyst reaches the activation temperature, it is excessively heated to the catalyst heat limit temperature. It is considered that due to this excessive temperature rise, the catalyst burns locally, causing melting and cracking.
[0014]
In the case of a large displacement engine, if the temperature rise is slow compared to a small displacement engine, the improvement in exhaust gas purification efficiency is naturally slower than that of a small displacement engine. Even after the catalyst reaches the activation temperature, the purification efficiency of the exhaust gas is not improved. That is, the purification efficiency is low even though the catalyst is sufficiently heated.
[0015]
In a large displacement engine, when estimating the mechanism of such a decrease in the catalyst temperature increase rate and the subsequent excessive temperature rise of the catalyst, the amount of air at the start increases as the engine displacement increases. It is considered that the exhaust gas speed in the exhaust manifold at the time of start-up becomes high, combustion in the exhaust manifold is not performed sufficiently, and the catalyst reaches the catalyst in a non-uniform combustion state.
[0016]
At the time of start-up, even if the throttle opening is small and a small amount of new inflow is present, it remains downstream of the throttle valve, that is, in the engine cylinder and in the intake system downstream of the throttle valve (particularly in the surge tank or resonator). A large amount of air is supplied into the cylinder and then flows out into the exhaust passage. That is, in the initial stage of the start, an amount of air is temporarily supplied that corresponds to the throttle valve being fully open. On the other hand, the fuel injection amount is normally set in accordance with the intake air amount. However, as described above, the intake air amount cannot be detected until a negative pressure is generated in the intake pipe at the initial start time. An amount of fuel corresponding to the intake amount corresponding to the throttle valve fully opened is injected.
[0017]
The flow passage cross-sectional area of the exhaust passage does not increase so much as the engine displacement increases, but the volume downstream of the throttle valve, mainly the engine cylinder volume and surge tank volume, increases according to the engine displacement. . Therefore, as the engine displacement increases, the amount of air at the time of start increases, and the exhaust gas speed in the exhaust manifold at the time of start increases.
[0018]
When the exhaust gas speed in the exhaust manifold is increased in this way, even if the exhaust manifold is provided with a volume (or a retention chamber), the time for the exhaust gas to stay in the exhaust manifold is shortened, and the fuel is contained in the exhaust gas. Even if unburned components remain, combustion of these unburned components becomes weak, and sufficient heat of combustion cannot be obtained, so it takes time to raise the temperature in the exhaust manifold. It is done.
[0019]
Further, when the exhaust gas speed in the exhaust manifold increases, the drift of the flow of unburned components and the flow of high-temperature combustion components becomes stronger, and the catalyst temperature distribution becomes uneven. As a result, the unburned component (HC) accumulates without burning mainly in the low temperature portion of the catalyst. It is considered that the unburned component (HC) deposited on the catalyst in this manner causes rapid local combustion when the catalyst reaches the ignition temperature, resulting in excessive temperature rise of the catalyst.
[0020]
The above-described problem can occur not only in a direct injection internal combustion engine but also in a port injection type (multipoint injection type) internal combustion engine.
By the way, Japanese Patent Laid-Open No. 2000-64889 discloses that when injecting additional fuel to activate a catalyst, the amount of intake air is reduced according to the temperature of the exhaust system to reduce the flow rate of exhaust gas. A technique for promoting early activation is disclosed. However, the influence of the air staying in the surge tank cannot be excluded at the start of startup, and the amount of intake air increases immediately after the start of startup. Therefore, the catalyst cannot be efficiently heated immediately after the start of startup. There is a problem.
[0021]
The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a start control device for an internal combustion engine that can efficiently raise the temperature of a catalyst immediately after the start of the start.
[0022]
[Means for Solving the Problems]
Therefore, an internal combustion engine start control device according to the present invention (claim 1) is provided in an expansion volume chamber provided downstream of a throttle valve in an intake passage, a fuel injection valve for injecting fuel into the engine, and an exhaust passage. And the control means for controlling the operation of the fuel injection valve. When the engine is started, the control means But To combustion of unburned components of fuel in exhaust gas and catalyst temperature distribution give Control is performed so that the operation of the fuel injection valve is started on the condition that the time when the influence decreases is reached.
Above Of the Retained air before starting But To combustion of unburned components of fuel in exhaust gas and catalyst temperature distribution give The effect is that when the amount of fuel corresponding to the intake amount corresponding to the throttle valve fully opened is injected at the time of starting the engine, the exhaust gas speed is increased by the accumulated air before starting in the expansion volume chamber. Combustion of the unburned component of the fuel becomes weak and combustion heat cannot be obtained sufficiently, and the drift of the flow of the unburned component and the flow of the high-temperature combustion component becomes strong and the catalyst temperature distribution becomes uneven.
In the start control device for an internal combustion engine of the present invention (Claim 2), Of the Retained air before starting Contributes to combustion of unburned components of fuel in exhaust gas and catalyst temperature distribution The time when the influence is reduced means that a predetermined time has elapsed after the start operation of the engine is started.
[0023]
Therefore, the substantial start-up operation of the engine (ie, the start of combustion) Contributes to combustion of unburned components of fuel in exhaust gas and catalyst temperature distribution It will be performed after the influence has been reduced (that is, after the stagnant air before start-up has been reduced), and immediately after start-up, the temperature of the exhaust gas purifying catalyst is promoted and overheating of the catalyst is prevented. And emission of exhaust gas until the catalyst is activated can be suppressed.
[0024]
In other words, when the engine is started, a large amount of pre-starting accumulated air in the expansion volume chamber flows into the combustion chamber. Therefore, if an amount of fuel corresponding to the amount of inflowing air is supplied to the combustion chamber and ignited, combustion is performed. Can do. However, if the exhaust gas velocity in the exhaust passage is high, the combustion of the unburned components of the fuel in the exhaust gas becomes weak, the catalyst temperature rises due to the combustion of the unburned components, and the drift of the combustion gas in the cylinder Occurs and the catalyst temperature distribution becomes uneven, so that unburned components accumulate in a part of the catalyst without burning, and the accumulated unburned components ignite when the catalyst temperature rises and abruptly appear on the catalyst. Local combustion occurs and the catalyst is overheated.
[0025]
On the other hand, in the start control device for an internal combustion engine of the present invention (claim 1), the stagnant air before start in the expansion volume chamber Contributes to combustion of unburned components of fuel in exhaust gas and catalyst temperature distribution Since the operation of the fuel injection valve is started after the influence decreases, that is, after the exhaust gas speed becomes slow, the unburned fuel component in the exhaust gas is sufficiently burned, This promotes the temperature rise of the catalyst. Further, in addition to sufficient combustion in this manner, combustion gas drift in the exhaust manifold and exhaust pipe does not occur, accumulation of unburned components on the catalyst is suppressed, and rapid local combustion on the catalyst is prevented. This prevents the catalyst from being overheated.
[0026]
The internal combustion engine start control device according to the present invention (claims) 3 ) Is a variable volume expansion chamber provided downstream of the throttle valve in the intake passage, a fuel injection valve for injecting fuel into the engine, an exhaust gas purification catalyst provided in the exhaust passage, and the fuel injection And control means for controlling the operation of the valve. When the engine is started, the control means is capacity Control is performed so that the operation of the fuel injection valve is started after the pressure is lowered.
[0027]
Therefore, the accumulated air before starting in the expansion volume chamber Contributes to combustion of unburned components of fuel in exhaust gas and catalyst temperature distribution Fuel injection at the start can be started while suppressing the influence, and as described above, immediately after the start, the temperature increase of the exhaust gas purifying catalyst can be promoted, and the excessive temperature increase of the catalyst thereafter can be prevented. Release of exhaust gas until the catalyst is activated can be suppressed.
In other words, when a large amount of pre-starting accumulated air in the expansion volume chamber flows into the combustion chamber when the engine is started, the exhaust gas velocity in the exhaust passage increases, and as described above, the unburned components of the fuel in the exhaust gas As the combustion of the catalyst becomes weaker, the temperature rise of the catalyst is delayed due to the combustion of the unburned components, and the drift of the combustion gas occurs in the cylinder and the catalyst temperature distribution becomes uneven. The accumulated unburned components are ignited without ignition, and when the catalyst temperature rises, they ignite and abrupt local combustion occurs on the catalyst, causing the catalyst to overheat.
[0028]
In contrast, the start control device for an internal combustion engine of the present invention (claims) 3 ) capacity Since the operation of the fuel injection valve is started after lowering the value, the exhaust gas speed is not fast, and the unburned fuel components in the exhaust gas are sufficiently burned, thereby promoting the temperature rise of the catalyst. The Further, in addition to sufficient combustion in this way, there is no drift of combustion gas in the exhaust manifold and exhaust pipe, the accumulation of unburned components on the catalyst is suppressed, and rapid local combustion on the catalyst is prevented. This prevents the catalyst from being overheated.
[0029]
Further, an intake air amount sensor for detecting an intake air amount to the engine is further provided, and the control means includes the intake air amount sensor. Emit output signal Further conditions that came to be As When the operation of the fuel injection valve is started and the amount of fuel injected from the fuel injection valve is controlled in accordance with the output signal from the intake air amount sensor, the fuel injection valve is appropriately operated from the start of operation. A small amount of fuel can be injected (claims) 4 ).
[0030]
Further, if the control means is configured to control the fuel injection valve so as to perform fuel injection for raising the temperature of the exhaust purification catalyst after the operation of the fuel injection valve is started, the catalyst is made more efficient. The temperature can be raised well. 5 ).
[0031]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
First, a start control device for an internal combustion engine as a first embodiment of the present invention will be described with reference to FIGS.
In a narrow sense, “start” means that after the starter switch is turned on, until the engine shifts from a state where it is rotationally driven by a starter motor to a state where it is rotationally driven by combustion explosive force (until complete explosion occurs). However, the start related to the start control is to be taken in a broad sense, and includes a period of time after the engine is completely detonated.
[0032]
First, the lean combustion engine according to the present embodiment will be described. The lean combustion engine is, for example, an in-cylinder injection engine (hereinafter also referred to as a direct injection gasoline engine or simply an engine) mounted on an automobile and mounted on the automobile. The configuration is as shown in FIG.
That is, the cylinder head 2 of the engine 1 is provided with a spark plug 4 and a fuel injection valve 6 that opens directly into the combustion chamber 5 for each cylinder 3. A piston 8 connected to the crankshaft 7 is provided in the cylinder 3, and a cavity 9 recessed in a hemispherical shape is formed on the top surface of the piston 8.
[0033]
An intake passage 11 that can communicate with the combustion chamber 5 via an intake valve 10 and an exhaust passage 13 that can communicate with the combustion chamber 5 via an exhaust valve 12 are connected to the cylinder head 2. Although not shown, the intake port is disposed substantially vertically above the combustion chamber 5, and forms a reverse tumble flow by intake air in the combustion chamber 5 in cooperation with the cavity 9 on the top surface of the piston 8. .
[0034]
A water temperature sensor 16 for detecting the cooling water temperature is provided on the water jacket 15 on the outer periphery of the cylinder 3, and a crank angle sensor 17 for outputting a signal at a predetermined crank angle position is provided on the crankshaft 7 with the intake valve 10 and the exhaust valve. A cylinder identification sensor (not shown) for outputting a cylinder identification signal corresponding to the camshaft position is attached to each camshaft (not shown) for driving the cylinder 12. Since the engine speed can be calculated based on the crank angle signal, the crank angle sensor 17 also functions as an engine speed detecting means.
[0035]
The intake passage 11 includes an air cleaner 21, an intake pipe 22, a throttle body 23, a surge tank (expansion volume chamber) 24, an intake manifold 25, and an intake port 11A in this order from the upstream side. A port (not shown) is provided. The throttle body 23 is provided with an electronically controlled throttle valve (ETV) 30 that adjusts the amount of air flowing into the combustion chamber 5. The ETV 30 electronically controls the throttle valve 30b by a throttle valve actuator (throttle valve driving means) 30a. The opening control of the ETV 30 is not only control according to the accelerator opening, but also idle speed control, which will be described later. It is also possible to control the introduction of a large amount of intake air during lean operation.
[0036]
Further, an air flow sensor (intake air amount sensor) 37 for detecting the intake air flow rate (intake air amount to the engine) is provided immediately downstream of the air cleaner 21, and a throttle position sensor for detecting the throttle opening of the ETV 30 in the throttle body 23. 38 and an idle switch 39 for detecting the fully closed state of the ETV 30 and outputting an idle signal, respectively.
[0037]
The exhaust system is composed of an exhaust port 13A, an exhaust manifold 26, and an exhaust pipe 27 in this order from the upstream side. As shown in FIGS. 31) and O ₂ A sensor 40 and an auxiliary catalyst (front catalyst) 32 for exhaust gas purification are provided in order from the upstream side. Further, a main catalyst (underfloor catalyst) 29 for exhaust gas purification is interposed in the exhaust pipe 27 downstream of these.
[0038]
Here, the exhaust manifold 26 itself is formed in an appropriate length as an independent exhaust passage for each cylinder, as in the prior art, and a staying portion 31 is formed in a collecting portion downstream of the exhaust manifold 26. However, as disclosed in Japanese Patent Application Laid-Open No. 11-294157 (particularly, FIG. 1), the exhaust manifold 26 is connected to the exhaust of each cylinder in such a conventional exhaust manifold (pipe connection type manifold). The pipes connecting the port and the end joining portion may be integrated to form a clamshell type, and the enlarged gathering portion may function as a retention portion (volume portion).
[0039]
Further, an accelerator position sensor (hereinafter referred to as APS) 42 for detecting an accelerator pedal depression amount (accelerator position) θap is provided.
Although the fuel supply system is not shown, the fuel whose pressure is adjusted to a predetermined high pressure (several tens of atmospheres (for example, about 2 to 7 MPa)) is guided to the fuel injection valve 6, and the high pressure fuel is supplied from the fuel injection valve 6. Is to be injected.
[0040]
In order to control the operation of each engine control element such as the spark plug 4, the fuel injection valve 6, and the ETV 30, an electronic control unit (ECU) 60 having a function as control means for the internal combustion engine is provided. The ECU 60 includes an input / output device, a storage device for storing a control program, a control map, etc., a central processing unit, a timer, a counter, and the like. Based on the position information and the like, the ECU 60 controls the engine control elements described above.
[0041]
In particular, this engine is an in-cylinder injection engine. Fuel injection can be performed at any timing, and uniform mixing is performed by fuel injection centered on the intake stroke to perform uniform combustion, and fuel injection centered on the compression stroke. Stratified combustion can be performed using the above-described reverse tumble flow. As the operation mode of this engine, O ₂ A stoichiometric mode in which the air-fuel ratio is maintained in the vicinity of the theoretical air-fuel ratio by feedback control based on detection information of the sensor 40, an enrichment mode in which the air-fuel ratio is richer than the stoichiometric air-fuel ratio, and the air-fuel ratio is significantly larger than the stoichiometric air-fuel ratio. There is provided a super lean mode in which lean lean combustion (super lean operation) is performed using the above-described stratified combustion.
[0042]
In the lean mode, fuel injection is performed in the compression stroke, and the injected fuel is partially collected only in the vicinity of the spark plug 4 by using the reverse tumble flow and the cavity 9 on the top surface of the piston 8. The part performs stratified combustion mainly in the state of only air, and while ensuring the ignitability of the fuel, the entire cylinder has an extremely lean air-fuel ratio to improve fuel efficiency.
[0043]
The ECU 60 selects one of the operation modes according to the target value (target Pe) of the engine effective speed Pe indicating the engine speed (hereinafter referred to as engine speed) Ne and the engine load state based on a preset map. When the engine speed Ne is small and the target Pe is small, the super lean operation mode (compressed lean operation mode) by stratified combustion is selected, and the engine speed Ne and the target Pe increase. The operation mode is selected in the order of stoichiometric and rich.
[0044]
The engine speed Ne is calculated from the output signal of the crank angle sensor 17, and the target Pe is calculated from the engine speed Ne and the accelerator opening θap detected by the accelerator position sensor 42.
By the way, the air sucked in according to the opening degree of the throttle valve 30b is sucked into the combustion chamber 5 from the intake port 11A by opening the intake valve 10, and directly injected from the fuel injection valve 6 based on a signal from the ECU 60. Mixed with fresh fuel. Then, the engine is combusted by ignition of the spark plug 4 at an appropriate timing to generate engine torque, and then the exhaust valve 12 is opened so that the exhaust gas is discharged from the combustion chamber 5 to the exhaust passage 13 as exhaust gas. CO, HC, NO in exhaust gas by catalyst 32, 29 _X After these three harmful components are purified, they are silenced by a muffler and desorbed to the atmosphere side.
[0045]
Here, focusing on the intake air, the outside air introduced through the air cleaner 21 is supplied to the combustion chamber 5 from the intake port 11A through the intake pipe 22, the throttle body 23, the surge tank 24, and the intake manifold 25. The amount of air to be supplied is usually in accordance with the opening degree of the throttle valve 30b provided in the throttle body 23, but even when the throttle valve 30b is in the idle opening degree (substantially fully closed) at the time of engine start. Since a large amount of air stored in the surge tank 24 is supplied, an air amount equivalent to the throttle fully opened is supplied.
[0046]
Focusing on the exhaust, the exhaust gas after combustion is exhausted from the exhaust port 13A through the exhaust manifold 26 and the exhaust pipe 27 and muffled by a muffler (not shown). At this time, the exhaust gas is provided downstream of the exhaust manifold 26. After temporarily staying in the staying portion 31 and burning the unburned components, it flows into the catalysts 32 and 29. In the combustion in the staying portion 31, while the exhaust gas flowing into the staying portion 31 stays while forming a vortex in the staying portion 31, the unburned components of the fuel mixed in the exhaust gas react with the residual oxygen. Is done.
[0047]
Of the two catalysts 32 and 29, the auxiliary catalyst 32 on the upstream side functions in particular when the engine is started when the main catalyst 29 on the downstream side is not activated. That is, since the auxiliary catalyst 32 is close to the combustion chamber 5, the exhaust gas flows in without being cooled and flows at a high temperature. Moreover, since the auxiliary catalyst 32 has a relatively small capacity, it is easy to activate it by quickly raising the temperature even with a small amount of heat. . In addition to this, the auxiliary catalyst 32 is located immediately below the staying portion 31, and high-temperature combustion heat in the staying portion 31 is also sent, so the temperature is raised and activated more quickly to purify the exhaust gas.
[0048]
Since the main catalyst 29 is far from the combustion chamber 5 and the staying portion 31 and has a relatively large capacity, it takes more time than the auxiliary catalyst 32 to raise the temperature to the activation temperature. It is easier to heat up than when there is no. Therefore, when the engine is started, first, the auxiliary catalyst 32 is activated quickly, and subsequently, the main catalyst 29 is activated. Immediately after startup, the engine is idling or low-load operation, and the small-capacity auxiliary catalyst 32 can sufficiently purify the exhaust gas. Thereafter, when the engine load increases, the large-capacity main catalyst 29 is also activated. The exhaust gas can be purified mainly by the main catalyst 29.
[0049]
Note that the main catalyst 29 is NO from the upstream side. _X A combination of a catalyst and a three-way catalyst may be used. That is, when the air-fuel ratio is lean, the exhaust gas contains almost no CO or HC, while NO. _X Concentration increases rapidly, but this NO _X NO functioning in an oxygen-rich atmosphere _X NO adsorbed by the catalyst and adsorbed in a reducing atmosphere (the air-fuel ratio is the stoichiometric or rich air-fuel ratio) _X CO, HC, NO in the exhaust gas by the three-way function of the three-way catalyst under the stoichiometric air-fuel ratio _X Is to purify. NO like this _X NO catalyst _X In the case of an occlusion type catalyst, a three-way catalyst may be further arranged upstream thereof. NO _X The catalyst is NO storage _X Selective NO in an oxygen-rich atmosphere rather than a catalyst _X Selective reduction type NO _X A catalyst may be used.
[0050]
By the way, in the start control device according to the present embodiment, the ECU (control means) 60 controls the operation of the fuel injection valve 6, but at this time, the effect of the stagnant air before start in the surge tank 24 decreases. The fuel injection valve 6 is operated on the condition that the air flow sensor (intake air amount sensor) 37 for detecting the intake air amount to the engine can detect the intake air amount (intake air flow rate). Is set to start. In other words, the operation of the fuel injection valve 6 is started when the exhaust gas speed becomes slow and a negative pressure is generated in the intake pipe 2 and the air flow sensor 37 issues an output signal. .
[0051]
As described above, when the engine is started, a large amount of pre-starting staying air in the surge tank (expansion volume chamber) 24 flows into the combustion chamber, and an amount of fuel corresponding to the amount of the inflowing air flows into the combustion chamber. If the exhaust gas speed in the exhaust passage is increased by increasing the engine displacement, etc., the unburned component of the fuel in the exhaust gas will reach the catalyst until it reaches the catalyst. Combustion is weakened, and the temperature rise of the catalyst is delayed due to vaporization of unburned components, and the drift of the combustion gas in the cylinder occurs, resulting in uneven catalyst temperature distribution.
[0052]
Therefore, one of the conditions for starting the operation of the fuel injection valve 6 is that the time when the influence of the stagnant air before starting in the surge tank 24 is reduced (the exhaust gas speed becomes slow at this time) is set. Yes. In general, after a predetermined time T1 has elapsed after the start operation of the engine (that is, after the starter switch is turned on), the influence of the accumulated air before the start in the surge tank 24 is reduced. The time until the influence of the stagnant air before starting in the surge tank 24 decreases is detected in advance, and a predetermined time T1 is set based on this time. After the start operation of the engine is started (that is, after the starter switch is turned on). When the predetermined time T1 has elapsed, it is determined that it is time to reduce the effect of the pre-starting accumulated air in the surge tank 24.
[0053]
Further, since the ECU 60 controls the operation of the fuel injection valve 6 [particularly, the drive time (fuel injection amount)] according to the intake air amount, the fuel injection valve 6 can be appropriately controlled if the intake air amount cannot be grasped. Can not. Here, the intake air amount is detected by the air flow sensor 37, but the sensor for detecting the intake air amount is generally provided on the upstream side of the throttle valve 30b, and a negative pressure is generated in the intake pipe, and the upstream side of the throttle valve 30b. The intake air amount cannot be detected unless a certain amount of intake air flows. In the initial stage of engine startup, no negative pressure is immediately generated in the intake pipe, and therefore the intake air amount cannot be detected during this period.
[0054]
Therefore, in order to control the fuel injection valve 6 with high accuracy, the fact that the air flow sensor 37 issues an output signal (that is, the intake air amount can be detected) is a condition for starting the operation of the fuel injection valve 6. One is set.
In addition, after the operation of the fuel injection valve 6 is started, the ECU 60 controls the fuel injection valve 6 to perform fuel injection for raising the temperature of the catalyst.
[0055]
As fuel injection for raising the temperature of the catalyst, in this embodiment, fuel injection control that realizes a combustion mode called two-stage combustion and fuel injection control that realizes a combustion mode called compression-slight lean combustion are performed. It has become. Both of these two-stage combustion and compressed slite lean combustion are combustion modes already described as conventional techniques.
[0056]
That is, in the two-stage combustion, as shown in FIG. 3, first, fuel injection for main combustion that applies rotational force to the engine (main injection, where main injection is compression stroke injection) is performed to perform main combustion. After that, additional fuel injection is performed separately from the main injection in the expansion stroke, and the additional fuel from the additional fuel injection is propagated to the main combustion flame. Or high temperature atmosphere Is ignited by the sub-combustion, the exhaust gas temperature is raised by the combustion heat, the warm-up of the catalyst is promoted, and the early activation is achieved. In this case, in one combustion cycle, the second combustion (sub-combustion) is performed after the main combustion.
[0057]
After the main combustion, additional fuel cannot be burned unless oxygen remains, so the main combustion needs to be leaner than stoichiometric, especially in the case of combustion with additional fuel (sub-combustion). In order to supply the amount of heat to the catalyst, here, the main combustion is stratified lean combustion (super lean combustion by compression stroke injection), and sub-combustion with additional fuel is performed.
[0058]
Compressed slight lean combustion involves directly injecting fuel into the combustion chamber during the compression stroke so that the air / fuel ratio of the engine is slightly leaner near the stoichiometric air / fuel ratio than the stoichiometric air / fuel ratio (this is called slight lean). As shown in FIG. 4, a technique has been proposed. The combustion mode in this case is referred to as compressed slender lean combustion.
[0059]
Thus, when fuel is injected during the compression stroke so that the air-fuel ratio of the engine is close to the stoichiometric air-fuel ratio to form stratified combustion (stratified combustion), the fuel is concentrated in one place and the air-fuel ratio is reduced. A rich air-fuel ratio is locally generated, incomplete combustion occurs, and a large amount of carbon monoxide (CO) is generated. On the other hand, surplus oxygen (O ₂ ), So these CO and O ₂ Are discharged into the exhaust passage at the same time, and the CO and O discharged in this way ₂ Both reach the catalyst through the exhaust passage, and the action of the catalyst causes CO and O ₂ Causes an oxidation reaction, and the catalyst heats up satisfactorily by this reaction heat.
[0060]
Here, when the engine is started, first, the ETV 30 is controlled so that an optimum air amount is obtained at the time of starting, and the air equivalent to the stoichiometry or richer than the stoichiometric air according to the intake air amount based on the output signal of the air flow sensor 37. The fuel is injected from the fuel injection valve 6 in an amount corresponding to the fuel ratio, and the engine start operation is performed by open loop control. When the start operation (meaning start in the narrow sense above) is completed (the engine speed reaches a predetermined speed). Then, under a predetermined condition, the two-stage combustion or the compressed slite lean combustion is performed. Here, the control of the fuel injection valve 6 during the start operation is performed based on a map in which the throttle opening at which the optimum start air amount is obtained and the fuel amount corresponding to the throttle opening are mapped in advance. Yes.
[0061]
By the way, the characteristic of the two-stage combustion is that the fuel to be additionally injected does not contribute to the engine output and is used only to raise the temperature of the exhaust gas flowing into the catalyst. Even if it is low, the temperature of the catalyst is easy to raise, so it is suitable for the initial stage when the engine is cold started. On the other hand, although the effect of raising the temperature of the catalyst efficiently while suppressing a decrease in fuel consumption is incurred in the compressed sllite lean combustion, the effect of raising the temperature of the catalyst is low when the temperature of the catalyst is low because the action of the catalyst itself is used. Not suitable for the initial stage when the engine is cold started.
[0062]
Thus, when the starting operation is completed, basically, the two-stage combustion is performed to raise the catalyst temperature, and then the compressed slur lean combustion is carried out to raise the catalyst temperature. Of course, both the two-stage combustion and the compressed sleek lean combustion are actually carried out when predetermined conditions are satisfied.
[0063]
For example, if a catalyst temperature sensor (high temperature sensor) for detecting the temperature of the catalyst is provided, the catalyst temperature T is based on the catalyst temperature detected by the high temperature sensor. _CC Is the predetermined temperature T _CC1 If it is in an inactive state at a very low temperature, the two-stage combustion is used and the catalyst temperature T _CC Is the predetermined temperature T _CC1 Higher than the predetermined temperature T _CC2 (However, T _CC1 <T _CC2 If it is in an inactive state lower than the <catalyst activation temperature lower limit value>, it is only necessary to use compressed slite lean combustion.
[0064]
Of course, the catalyst temperature T _CC When the catalyst reaches the lower limit of the catalyst activation temperature, these processes are stopped and the routine shifts to normal engine control. Further, even during the two-stage combustion or the compression-slight lean combustion, if any one of the engine rotational speed Ne, the target average effective pressure Pe, and the vehicle speed V exceeds the corresponding predetermined value, the two-stage combustion or Catalyst temperature T _CC Therefore, it is preferable to stop the two-stage combustion or the compression slur lean combustion and shift to normal engine control.
[0065]
Since the internal combustion engine start control device according to the first embodiment of the present invention is configured as described above, when starting the engine, for example, as shown in FIG. Tank), a predetermined time T1 has elapsed after the start operation of the engine (that is, after the starter switch is turned on) (discharge time). (Step A1), and whether or not the intake air amount can be detected, that is, whether or not the air flow sensor 37 has started to output an output signal (step A2). It is time to reduce the influence of the stagnant air before startup in the expansion volume chamber (surge tank) 24, and the intake air amount can be detected. Fuel starts operation of the fuel injection valve 6 to be injected (step A3). During the starting operation, the throttle opening degree is controlled based on a map corresponding to the water temperature, the intake air temperature, and the intake air density so that the throttle opening degree at which the optimum starting air amount can be obtained.
[0066]
Therefore, fuel injection is not performed under a situation where the influence of the pre-starting accumulated air in the expansion volume chamber (surge tank) 24 is large or when the intake air amount cannot be detected. If the influence of the pre-starting air in the expansion volume chamber (surge tank) 24 becomes strong due to the engine displacement being increased, etc., and the exhaust gas velocity in the exhaust passage is increased, the unburned components of the fuel in the exhaust gas Although the combustion becomes weak and the temperature rise of the catalyst is delayed due to the combustion of unburned components, and the drift of the combustion gas occurs in the cylinder and the catalyst temperature distribution becomes uneven. Below, since fuel injection is not performed, such a malfunction is avoided.
[0067]
Further, if the intake air amount cannot be grasped, the fuel injection valve 6 cannot be properly controlled, but the intake air amount can be detected. (That is, the air flow sensor 37 emits an output signal) Since the fuel injection valve 6 is operated for the first time, the fuel injection valve 6 can be accurately controlled.
FIG. 6 is a graph showing temporal changes in the temperature in the exhaust manifold (exhaust manifold), the catalyst temperature, and the exhaust gas purification efficiency when the engine according to the present embodiment is started. Each solid line relates to a small displacement engine. Each chain line (one point chain Line) relates to a large displacement engine. The horizontal axis represents time, and the two-stage combustion and the compressed slite lean combustion are shown in correspondence with each other above.
[0068]
As shown in the figure, in the conventional large displacement engine, the improvement in exhaust gas purification efficiency was extremely slow (see FIG. 9), whereas in the large displacement engine according to this embodiment, the small displacement engine Compared to, the exhaust gas purification efficiency improves immediately after starting, although it is slightly slower.
Further, in the large displacement engine according to the present embodiment, the temperature in the exhaust manifold increases in substantially the same manner as in the small displacement engine, and the catalyst temperature increases at a speed close to that of the small displacement engine even in the large displacement engine. In addition, it can be seen that the catalyst is maintained in a certain temperature range after reaching the activation temperature (temperature lower limit value at which the catalyst becomes active) and does not overheat to the catalyst heat limit temperature.
[0069]
It should be noted that it takes a short time until the influence of the pre-starting accumulated air in the expansion volume chamber (surge tank) 24 decreases after the engine is started or until the intake air amount can be detected. Never give.
Rather, immediately after startup, the temperature increase of the catalysts 32, 29 can be promoted, the subsequent excessive temperature increase of the catalysts 32, 29 can be prevented, and the exhaust gas released until the catalysts 32, 29 are activated. Therefore, it is possible to obtain an extremely favorable effect on the global environment that exhaust gas purification at the start of the engine can be promoted.
[0070]
In the present embodiment, the ECU 60 controls the fuel injection valve 6 to increase the temperature of the catalyst after the operation of the fuel injection valve 6 is started. Specifically, the ECU 60 performs two-stage combustion, compression slur lean Since the fuel injection for combustion is executed, the temperature increase of the catalysts 32 and 29 is promoted after the operation of the fuel injection valve 6 is started. First, the front catalyst 32 is activated quickly, and then the underfloor catalyst. 29 is activated quickly, so that exhaust gas purification from an earlier stage can be realized when the engine is started.
[0071]
In particular, under conditions where the temperature of the catalyst is low and the effect of temperature rise is small in compressed slender lean combustion, the temperature of the catalyst is quickly raised using two-stage combustion. If a temperature rise effect of a certain level or more can be obtained even in compressed sllite lean combustion, temperature rise control with good fuel efficiency is performed using compressed sllite lean combustion, so that the catalyst temperature can be promoted while minimizing the reduction in fuel efficiency. You can do it.
[0072]
By the way, when there is no high temperature sensor that detects the temperature of the catalyst, the conditions for the two-stage combustion and the conditions for the compression / slight lean combustion are set as follows, and when these are satisfied, each combustion control is performed. May be implemented.
That is, in order to execute the two-stage combustion, (1) the idle switch is on (idling), (2) the engine rotational speed Ne, the target average effective pressure Pe, and the vehicle speed V are all corresponding. (3) The cooling water temperature information WT detected by the water temperature sensor 16 is a temperature at which the engine 1 can be considered to be warmed up, that is, the warming temperature WT0 or less, (4) Two-stage The execution condition is that each of the conditions of being within a predetermined time T2 after the start of combustion is satisfied.
[0073]
In addition, in order to execute the compression / slight lean combustion, (5) the engine rotational speed Ne, the target average effective pressure Pe, and the vehicle speed V are all equal to or less than the corresponding predetermined values, and (6) the water temperature sensor 16 detects. The cooling water temperature information WT is the temperature at which the engine 1 can be regarded as being warmed up, that is, the warming-up temperature WT0 or lower, and (7) within the predetermined time T3 after the start of the compression slur lean combustion. Satisfying each condition is an execution condition.
[0074]
The first condition (1) of the two-stage combustion is that if the engine is idling immediately after the engine is started, the catalyst temperature is low, and the temperature of the catalyst can be increased more efficiently and reliably in the two-stage combustion than in the compression sludge lean combustion. This is because it can.
The second condition (2) for the two-stage combustion and the first condition (5) for the compression slean lean combustion are usually high when the engine speed Ne, the target average effective pressure Pe, or the vehicle speed V is high. This is because it can be regarded as a traveling state, and the temperature raising effect of the catalyst can be sufficiently obtained without using the two-stage combustion or the compressed slite lean combustion. However, this condition (2) (4) is normally satisfied when the engine is cold-started.
[0075]
The third condition {circle around (3)} for two-stage combustion and the second condition {circle around (6)} for compressed slender lean combustion take into consideration the prevention of overheating of the catalyst. However, this condition (3) (5) is normally satisfied when the engine is cold-started.
Further, the fourth condition (4) of the two-stage combustion is that, when the two-stage combustion is performed, the temperature of the catalyst is increased and the temperature of the catalyst can be increased efficiently by the compression sludge lean combustion. The time that will reach the temperature suitable for the compression slur lean combustion is obtained in advance by experiments, etc., and this is set as the above predetermined time T2, and when the temperature of the catalyst rises to some extent, the transition from the two-stage combustion to the compression slur lean combustion Like to do.
[0076]
Further, the third condition (7) of the compressed sllite lean combustion is that the temperature of the catalyst will rise sufficiently when the compressed slrite lean combustion is performed. This is set as the above-mentioned predetermined time T3, and when the temperature of the catalyst is sufficiently raised, the combustion is shifted from the compression slur lean combustion to the normal combustion.
[0077]
Therefore, when the starting operation is completed, first, the temperature of the catalyst is increased by performing two-stage combustion, or is the start operation performed (see condition (1)), or when the temperature of the catalyst is increased to some extent (see condition (4)), The temperature of the catalyst is increased by carrying out the compression slight lean combustion from the two-stage combustion. Even during this time, when the engine speed, the engine rotation load, or the vehicle speed increases, the normal control (stoichiometric mode or enrichment mode) is started.
[0078]
Of course, the fuel injection for raising the temperature of the catalyst performed after the start of the operation of the fuel injection valve 6 may be performed only in either one of the two-stage combustion and the compression slight lean combustion, depending on other fuel injection modes The temperature of the catalyst may be raised.
Next, a start control device for an internal combustion engine as a second embodiment of the present invention will be described based on FIGS. FIG. 7 is a diagram corresponding to FIG. 1, and the same reference numerals denote the same components, and description thereof will be omitted.
[0079]
As shown in FIG. 7, in this embodiment, a surge tank 24a and a resonator 24b communicating with the surge tank 24a are provided as an expansion volume chamber, and a valve 24c is provided between the surge tank 24a and the intake pipe 22. Is provided. An appropriate number (three in this case) of the resonators 24b is provided. When the valve 24c is opened, the surge tank 24a and the resonator 24b communicate with the intake pipe 22, and effects such as relaxation of intake interference, improvement of intake inertia effect, and suppression of intake system resonance noise can be obtained.
[0080]
On the other hand, when the valve 24c is closed, communication between the surge tank 24a and the resonator 24b with the intake pipe 22 is blocked, and the above effect cannot be obtained. The valve 24c is closed when the engine is started, and this control is performed for the following reason.
In other words, when the engine is started, a large amount of pre-starting accumulated air in the surge tank 24a or the resonator 24b, which is an expansion volume chamber, is discharged by increasing the exhaust gas speed in the exhaust passage when the engine displacement is increased. The combustion of the unburned components of the fuel in the gas is weakened, the temperature rise of the catalyst due to the burning of the unburned components is delayed, and the drift of the combustion gas in the cylinder is caused, causing the catalyst temperature distribution to become uneven.
[0081]
Therefore, in the start control device according to the present embodiment, when there is an engine start command (when the starter switch of the engine is turned on), the ECU (control means) 60 first closes the valve 24c and sets the surge tank 24a and The communication of the resonator 24b with the intake pipe 22 is cut off to eliminate the influence of a large amount of accumulated air before starting in the surge tank 24a and the resonator 24b, and further, an air flow for detecting the amount of intake air to the engine The sensor (intake air amount sensor) 37 can detect the intake air amount (intake air flow rate). (In other words, it came to emit an output signal) On this condition, the fuel injection valve 6 is set to start operating.
[0082]
That is, by eliminating the influence of a large amount of stagnant air before starting in the surge tank 24a and the resonator 24b, the exhaust gas speed is slowed, and negative pressure is generated in the intake pipe 2 so that the air flow sensor 37 outputs an output signal. Is set to start the operation of the fuel injection valve 6.
In the first embodiment, the air flow generated by the movement of the piston 8 driven by the starter motor waits for the air in the surge tank 24 to be discharged, whereas in the second embodiment, the surge tank 24a. In addition, the communication of the resonator 24b with the intake pipe 22 is cut off, so that the influence of air in the surge tank 24a and the resonator 24b is positively eliminated.
[0083]
Other than this, the configuration is the same as in the first embodiment.
In this case, the surge tank 24a and the resonator 24b can be selected to use or not. However, the capacity of the surge tank can be adjusted (that is, as a variable capacity type surge tank). ) At startup, the surge tank capacity may be reduced (minimum is preferred).
[0084]
Since the internal combustion engine start control device according to the second embodiment of the present invention is configured as described above, when starting the engine, for example, as shown in FIG. (Volume of the tank) 24a is reduced (here, the volume is substantially 0) (step B1), and whether or not the intake air amount can be detected, that is, whether or not the air flow sensor 37 has come to output an output signal. The operation of the fuel injection valve 6 is started only after the determination (step B2) is made and the intake air amount can be detected (step B3).
[0085]
Thus, the internal combustion engine start control apparatus according to the second embodiment can achieve the same effects as those of the first embodiment, and in particular, positively eliminates the influence of air in the surge tank 24a and the resonator 24b. Then, since the operation of the fuel injection valve 6 is started, there is an effect of increasing the possibility that the operation of the fuel injection valve 6 can be started more quickly than in the first embodiment.
[0086]
In addition, all the above-mentioned embodiment is an example, Comprising: This invention is not limited to this embodiment, In the range which does not deviate from the meaning of this invention, it carries out various deformation | transformation of the above-mentioned embodiment. Can do.
For example, in each of the above embodiments, the front catalyst 32 is provided, but the above effect can be obtained at a certain level even if the front catalyst 32 is omitted and only the underfloor catalyst 29 is provided.
[0087]
Further, the technology according to the present invention can be applied not only to an in-cylinder injection engine but also to a port injection engine. In this case, the compression-slight lean combustion cannot be applied, but the two-stage combustion can be applied by utilizing the overlap between the intake valve and the exhaust valve. That is, if the intake valve is opened before the exhaust valve is closed in the exhaust stroke, an overlap state occurs in which both the intake valve and the exhaust valve are opened. At this time, if additional fuel injection is performed, Combustion corresponding to sub-combustion can be performed, and two-stage combustion can be realized.
[0088]
【The invention's effect】
As described above in detail, according to the start control device for an internal combustion engine of the present invention (Claim 1), at the time of starting the engine, the control means is the stagnant air before start in the expansion volume chamber. Contributes to combustion of unburned components of fuel in exhaust gas and catalyst temperature distribution Since the control is performed so that the operation of the fuel injection valve is started on the condition that the time when the influence is reduced, the substantial start operation of the engine (that is, the start of combustion) Contributes to combustion of unburned components of fuel in exhaust gas and catalyst temperature distribution It will be performed after the influence has been reduced (that is, after the stagnant air before start-up has been reduced), and immediately after start-up, the temperature of the exhaust gas purifying catalyst is promoted and overheating of the catalyst is prevented. And emission of exhaust gas until the catalyst is activated can be suppressed, and purification of exhaust gas can be promoted.
[0089]
According to the start control device for an internal combustion engine of the present invention (Claim 3), at the time of engine start, the control means operates the fuel injection valve after reducing the capacity of the expansion volume chamber at the time of start of the engine. Since it is controlled to start, the accumulated air before starting in the expansion volume chamber Contributes to combustion of unburned components of fuel in exhaust gas and catalyst temperature distribution Fuel injection at the start can be started while suppressing the influence, and as described above, immediately after the start, the temperature increase of the exhaust gas purifying catalyst can be promoted, and the excessive temperature increase of the catalyst thereafter can be prevented. Release of exhaust gas until the catalyst is activated can be suppressed, and purification of exhaust gas can be promoted.
[0090]
Further, an intake air amount sensor for detecting an intake air amount to the engine is further provided, and the control means includes the intake air amount sensor. Emit output signal Further conditions that came to be As When the operation of the fuel injection valve is started and the amount of fuel injected from the fuel injection valve is controlled in accordance with the output signal from the intake air amount sensor, the fuel injection valve is appropriately operated from the start of operation. Fuel can be injected and the exhaust gas level immediately after starting can be improved. 4 ).
[0091]
Further, if the control means is configured to control the fuel injection valve so as to perform fuel injection for raising the temperature of the exhaust purification catalyst after the operation of the fuel injection valve is started, the catalyst is made more efficient. The temperature can be raised well and the purification of exhaust gas can be promoted (claims) 5 ).
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram showing an internal combustion engine according to a first embodiment of the present invention.
FIG. 2 is a schematic front view showing an exhaust manifold of the internal combustion engine according to the first embodiment of the present invention.
FIG. 3 is a diagram illustrating two-stage combustion according to the first embodiment of the present invention.
FIG. 4 is a diagram for explaining compression slur lean combustion according to the first embodiment of the present invention.
FIG. 5 is a flowchart illustrating start control according to the first embodiment of the present invention.
FIG. 6 is a diagram for explaining the effect of start control according to the first embodiment of the present invention.
FIG. 7 is a schematic configuration diagram showing an internal combustion engine according to a second embodiment of the present invention.
FIG. 8 is a flowchart illustrating start control according to the second embodiment of the present invention.
FIG. 9 is a diagram illustrating a problem of conventional start control.
[Explanation of symbols]
24, 24a Surge tank (expansion volume chamber)
24b Resonator (Extended volume chamber)
29 Underfloor catalyst (exhaust gas purification catalyst)
32 Front catalyst (exhaust gas purification catalyst)
37 Airflow sensor (intake air amount sensor)
60 ECU (control means)

Claims (5)

An expansion volume chamber provided downstream of the throttle valve in the intake passage;
A fuel injection valve for injecting fuel into the engine;
An exhaust gas purifying catalyst provided in the exhaust passage;
Operation of the expansion volume chamber of prestart residence air fuel injection valve on the condition that the effect has become time to decrease to provide to the combustion and the catalyst temperature distribution of the unburned components of the fuel in the exhaust gas at the time of starting of the engine And a starting control device for an internal combustion engine. Above, and the effect of the pre-start dwell air gives to the combustion of the unburned components fuel and catalyst temperature distribution in the exhaust gas becomes time to decrease, after the starting operation start of the engine, a predetermined time has elapsed The start control device for an internal combustion engine according to claim 1, wherein A variable volume expansion volume chamber provided downstream of the throttle valve in the intake passage;
A fuel injection valve for injecting fuel into the engine;
An exhaust gas purifying catalyst provided in the exhaust passage;
A start control device for an internal combustion engine, comprising: control means for starting the operation of the fuel injection valve after reducing the capacity of the expansion volume chamber at the start of the engine. Equipped with an intake air amount sensor for detecting the intake air amount to the engine,
The control means starts the operation of the fuel injection valve on the condition that the intake air amount sensor emits an output signal, and the fuel injection valve according to the output signal from the intake air amount sensor. The start control device for an internal combustion engine according to any one of claims 1 to 3, wherein the amount of fuel injected from the engine is controlled. 4. The fuel injection valve according to claim 1, wherein the control means controls the fuel injection valve so as to execute fuel injection for raising the temperature of the exhaust purification catalyst after the operation of the fuel injection valve is started. An internal combustion engine start control device according to any one of the preceding claims.

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